1. Field of the Invention
The present invention relates to an ultrasonic inspection apparatus, and more particularly, relates to a digital type ultrasonic inspection apparatus reducing the dead time in the scan operation of a scanner to zero by utilizing large-volume data transfer.
2. Description of the Related Art
A conventional general analog-type ultrasonic inspection apparatus will be explained first referring to FIG. 3. A sample or an inspected object 101 is placed in the water of a water tank 102. The water tank 102 is placed on a measurement stage 103. A scanner 104 is placed on the water tank 102. The scanner 104 is attached to the measurement stage 103. The scanner 104 is comprised of an X-axis scanner 105, Y-axis scanner 106 and Z-axis scanner 107. The Z-axis scanner 107 is provided at its bottom with an ultrasonic probe 108. The tip of the ultrasonic probe 108 faces the sample 101 at the bottom side. The X-axis, Y-axis and Z-axis as axes of the scan operation of the scanner 104 are perpendicular to each other. The operations of the X-axis scanner 105, Y-axis scanner 106 and Z-axis scanner 107 are controlled by a motor controller 109. Under the control of the motor controller 109, the scanner 104 independently scans along the X-axis, Y-axis and Z-axis. The motors of the scanner 104 for the three axes have encoders 110 respectively. The encoders 110 for the X-axis, Y-axis and Z-axis output trigger signals indicating the positional coordinates on the X-axis, Y-axis, and Z-axis by resolutions set in advance.
A pulser/receiver circuit 111 transmits a drive pulse signal to the ultrasonic probe 108 and receives a reflection echo signal from the ultrasonic probe 108. An analog peak detector 112 extracts the reflection echo signal relating to a desired inspection surface from the reflection echo signal received through a gate circuit and holds the peak value. An A/D conversion circuit 113 converts the analog peak values of the reflection echo signal to digital values while linking them with the trigger signals output from the encoders 110. A computer 114 is comprised of a CPU 115, keyboard 116, and main memory 117. The computer 114 controls the motor controller 109. Further, the computer 114 stores the digital peak values of the reflection echo signal in the main memory 117 through a data bus 118 and further displays the peak values on a monitor 119 in accordance with the planar coordinates. The data stored in the main memory 117 is used for various types of data processing. In addition, the pulser/receiver circuit 111 is similarly connected to an oscilloscope 120.
In the ultrasonic inspection apparatus shown in FIG. 3, the X-axis scanner 105 and the Y-axis scanner 106 scan planarly, while the ultrasonic probe 108 transmits an ultrasonic pulse toward the sample 101 based on the drive pulse signal given from the pulser/receiver circuit 111. The ultrasonic probe 108 receives the reflection echo signal returned from the sample 101. Using the received reflection echo signal, the analog peak detector 112 holds the peak values of the reflection echo signal near the desired inspection surface. The A/D conversion circuit 113 uses position trigger signals output from the encoders 110 to sample the data. Next, the computer 114 obtains the data, then displays an image based on the obtained signal on the monitor 119. In this way, a picture of the desired inspection surface in the sample 101 is obtained.
There are two methods as shown in FIG. 2A and FIG. 2B for the X-axis and Y-axis planar scan by the X-axis scanner 105 and Y-axis scanner.
The method of measurement shown in FIG. 2A includes the step of having the A/D conversion circuit 113 use the position trigger signals output from the encoders 110 during a two-directional scan to sample data and the step of having the computer 114 display an image of the inspection surface echo signal obtained on the monitor 119. In this way, a picture of the desired inspection surface of the sample 101 is obtained on the monitor 119. This measurement method requires that before the feed scan in the Y-direction by the Y-axis scanner 106 is completed and the return scan of the X-direction by the X-axis scanner 105 is started, the transfer of data from the A/D conversion circuit 113 to the computer 114 be completed and the A/D conversion circuit 113 can sample the data during the return scan.
The method of measurement shown in FIG. 2B includes the step of having the A/D conversion circuit 113 use the position trigger signals output from the encoders 110 to sample data during the scan in the same direction at all times for the X-direction, and the step of having the computer 114 display an image based on the obtained inspection surface echo signal on the monitor 119. In this way, a picture of the desired inspection surface of the sample 101 is obtained on the monitor 119. This measurement method makes it possible to simultaneously perform a feed scan in the Y-direction by the Y-axis scanner 106 and return scan in the X-direction by the X-axis scanner 105. Further, it requires that, before the start of the next X-axis outgoing scan, the transfer of the data from the A/D conversion circuit 113 to the computer 114 be completed and the A/D conversion circuit 113 can sample data at the time of the next outgoing scan.
The number of the two-directional scans in the X-direction in the scan method of FIG. 2A is half that of the number in the scan method of FIG. 2B. Accordingly, in general, it is known that the scan time in FIG. 2A is shorter than the scan time in FIG. 2B.
As explained above, the analog type ultrasonic inspection apparatus shown in FIG. 3 can extract the peak values of a reflection echo signal of a desired inspection surface and produce a picture of the peak values. This ultrasonic inspection apparatus, however, requires several analog peak detectors when trying to simultaneously obtain peak values of reflection echo signals of several inspection surfaces. Further, when the ultrasonic inspection apparatus has several analog peak detectors, the problems of variations in the circuit characteristics among the detectors and the detection gate technology for reliably separating the echoes arise.
To solve these problems, a digital type ultrasonic inspection apparatus has been proposed. This digital type ultrasonic inspection apparatus uses a high speed A/D converter to convert the reflection echo signals to digital data and performs the gating and peak detection of the reflection echo signals at the desired positions digitally to instantaneously obtain information of several inspection surfaces.
FIG. 4 shows an example of the digital type ultrasonic inspection apparatus. In FIG. 4, components in common with those of the analog type ultrasonic inspection apparatus explained above are assigned the same reference numerals for convenience in explanation. The digital type ultrasonic inspection apparatus has a peak detection program 121 within the memory of the computer 114 instead of the analog peak detector 112 of the analog type ultrasonic inspection apparatus. Further, instead of the A/D conversion circuit 113, an A/D converter 122 is provided. The A/D converter 122 is comprised of an A/D conversion circuit 122a and a memory 122b. 
In the digital type ultrasonic inspection apparatus shown in FIG. 4, the A/D converter 122 samples the waveform data of several hundred to several thousand of points from the surface to the bottom of the sample 101 for each position trigger signal output from the encoders 110. The large number of waveform data sampled is stored in the memory 122b. The computer 114 performs the gating of the waveforms and the detection of the peak values of the desired inspection surface for the waveform data stored in the main memory 117 by the peak detection program 121. And it displays the digital peak values of the reflection echo signal of the desired inspection surface on the monitor 119. Due to this, a picture of an inspection surface in the sample 101 is obtained. The above-mentioned two planar scan measurement methods of FIG. 2A and FIG. 2B can be similarly used in the digital type ultrasonic inspection apparatus as well.
As explained above, in both the analog type and digital type ultrasonic inspection apparatus, the individual sampled data obtained based on the position trigger signals output from the encoders 110 are arranged as shown in FIGS. 2A and 2B. In particular, in the analog type ultrasonic inspection apparatus, peak detection values in the gates at the positions X1xe2x88x921, X1xe2x88x922, . . . , Xmxe2x88x92n corresponding to the arrangement of the sampling positions, that is, the digital peak values, are sampled at those positions. The digital peak values are for example 1 byte of peak value data.
On the other hand, in the digital type ultrasonic inspection apparatus, since a program is used for peak detection, digital data of waveforms at the positions X1xe2x88x921, X1xe2x88x922, . . . , Xmxe2x88x92n corresponding to the arrangement of the sampling positions, for example, the waveform data of several hundred to several thousands of points (for example, unit: bytes), are sampled at those positions. Therefore, the number of points of data sampled in the digital type ultrasonic inspection apparatus becomes several hundred to several thousand times the amount of data sampled in the analog type ultrasonic inspection apparatus. Therefore, when configuring the digital type ultrasonic inspection apparatus, in particular in the case of FIG. 2A, it is required that before the feed scan in the Y-direction and the return scan in the X-direction are started, the transfer of data from the memory 122b of the A/D converter 122 to the computer 114 be completed and the A/D converter 122 can sample data at the time of the return scan. Therefore, the digital type ultrasonic inspection apparatus requires technology for a high-speed data transfer system.
In the above-explanation, the problems in the planar scan by the ultrasonic inspection apparatus were explained. However, the problems are not limited to the planar scan. The above problems similarly occur in spiral rotational scans or inclined scans by the ultrasonic inspection apparatus.
An object of the present invention is to provide an ultrasonic inspection apparatus of a digital type realizing a system of high speed data transfer not affecting data sampling at the time of scanning in, for example, a two-directional type planar scan, enabling transfer of a high volume of data, and thereby reducing the dead time at the time of scanner scans to zero to enable measurement by high speed scans.
The ultrasonic inspection apparatus according to the present invention is configured as follows to achieve the above object.
The first ultrasonic inspection apparatus of the invention scans a sample by an ultrasonic probe by scanners of at least two axes, transmits an ultrasonic wave from the ultrasonic probe toward the sample, and receives the reflection echo signal returning from the sample. The waveforms received at the A/D converter are converted to digital waveform data with each sampling position trigger output from the encoders of the scanners. The digital waveform data output from the A/D converter is transferred to the computer where it is processed in various ways. The ultrasonic inspection apparatus is further provided with at least two data memories controlled in operating states by a scan state monitoring signal setting a unit measurement range in accordance with the operating state in advance and changing with each change of the unit measurement range when continuously scanning a plurality of unit measurement ranges and a memory controller for receiving as input a trigger signal based on the detection values of the above encoders, changing the scan state monitoring signal with each change of the unit measurement range, and outputting the scan state monitoring signal to the at least two data memories. In the above configuration, the memory controller controls the operation states of the at least two data memories based on the scan state monitoring signal, that is, performs control to alternately write digital waveform data from the A/D converter to a data memory, read digital waveform data from a data memory by the computer, and transfer data to the memory of the computer.
The second ultrasonic inspection apparatus that has the configuration of the above-mentioned first apparatus, is preferably configured such that the memory controller is provided with a counter for counting the number of the position triggers determined by encoders corresponding to the sampling position coordinates when scanning a unit measurement range, a comparator-register for comparing the count of the counter and the number of position triggers in the set unit measurement range and outputting a signal for changing the scan state monitoring signal each time the results of the comparison are a match, and a memory-control-circuit for outputting a scan state monitoring signal for controlling the operating states of the at least two data memories based on the signal given from this comparator-register.
The third ultrasonic inspection apparatus that has the configurations of the above apparatuses, is preferably configured such that the at least two data memories are comprised of a first data memory and second data memory and the memory controller outputs a scan state monitoring signal of a first state and second state. When the scan state monitoring signal is the first state, it is possible to write data into the first data memory and read out data from the second data memory. The digital waveform data outputted from the A/D converter is continuously written into the first data memory, and simultaneously the digital waveform data is continuously read out from the second data memory in the computer. When the scan state monitoring signal is the second state, it is possible to read out data from the first data memory and write data into the second data memory. The digital waveform data obtained by sampling operation of the A/D converter is continuously written into the second data memory, and simultaneously the digital waveform data is continuously read out from the first data memory.
The fourth ultrasonic inspection apparatus that has the configuration of the above apparatuses, is preferably configured such that the second data memory write-enabled by the change of the scan state monitoring signal from the first state to the second state is continuously written with data from the digital waveform data after the final digital waveform data in the first data memory write-enabled when the scan state monitoring signal is the first state so as to preserve the continuity of data stored between the first data memory and second data memory.
The fifth ultrasonic inspection apparatus that has the configuration of the above apparatuses, is preferably configured such that the computer is provided with means for storing the digital waveform data read out from the at least two data memories at addresses corresponding to the sampling positions on the memory of the computer. Due to this means, the data is transferred continuously from the data memories to addresses on the memory of the computer by direct memory access (DMA).
In the configuration of the ultrasonic inspection apparatus according to the present invention, the waveform data obtained by the measurement is processed digitally. The reflection echo returned from the inspected object or the sample is received by an ultrasonic probe and converted into an electric analog signal. The analog signal is converted (digitalized) to digital waveform data at several hundred to several thousand of points of the waveform from the sample surface to bottom using a high speed A/D converter for each position trigger corresponding to a sampling position output from the encoders of the scanners.
In the digital type ultrasonic inspection apparatus according to the present invention, the converted digital waveform data is temporarily stored in the data memory section, then transferred to the memory of the computer for storage. The data memory section is comprised of at least two data memories. In the measurement scan, since a large amount of digital waveform data of several hundred to several thousand of points is prepared and stored, a unit measurement range corresponding to a scan operation is set and a data memory for storing the waveform data is selected and temporarily stored-in based on a switching operation by the memory controller. Due to this, it is possible to continuously perform measurement scans, sample waveform data by the A/D converter, and transfer digital waveform data from the data memories to the computer side memory by the computer without stopping. Therefore, it is possible to eliminate loss time due to transfer of data.
When the sample scan at the ultrasonic inspection apparatus according to the present invention is a planar scan for a representative XY plane, a two-dimensional scan by the X-axis scanner and Y-axis scanner is performed. During the two-dimensional scan, it is possible to continuously sample waveform data through the A/D converter and transfer digital waveform data from the data memories to the computer side memory by the computer without stopping. In this case, after the first line scan operation in the X-direction by the X-axis scanner and the feed operation in the Y-direction by the Y-axis scanner after that, without waiting for the end of the transfer of the first line digital waveform data, a second line X-direction scan and the later Y-direction feed become possible, so it is possible to eliminate loss time due to transfer of data.
In the case of a planar scan of the XY plane, the above-mentioned xe2x80x9cunit range of measurementxe2x80x9d is, for example, one line in the X-direction. In this case, the odd numbered one-line scan portions become odd-numbered measurement ranges, while the even-numbered one-line scan portions become even-numbered one-line scan portions. The changes in the two signal shapes of a scan state monitoring signal arise in accordance with changes from the even-numbered measurement range from the odd-numbered measurement range or changes from the odd-numbered measurement range from the even-numbered measurement range.